JPS60140106A - Shape inspection apparatus - Google Patents

Abstract

PURPOSE:To easily judge the quality of a pattern shape, by setting a level so as to independently bringing a conversion part of a shape to be measured to an electric signal and a reference signal including a tolerance range in the positional shift of the shape to be measured to a definite ratio. CONSTITUTION:A shape 19 to be measured is converted to an electric signal by an ITV camera 20 and a reference shape 21 is converted to an electric signal by an ITV camera while both signals are subjected to level setting by level setting circuits 23, 24. At this time, the reference shape 21 shows a shape 30 in a tolerance range larger than the reference shape 29 of the shape to be measured and a shape 31 in a tolerance range smaller than that as the difference of electric signals. These signals are synthesized by a mixer circuit 25 and the increase or decrease at a definite ratio of the change in the level of the synthesized signal is detected by a level difference detection circuit 26 and the appearing sequence of level difference is detected by a quality detection circuit 27 to perform the judgement of the quality of a shape.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an apparatus for determining the acceptability of the shape and positional deviation of a pattern of a semiconductor device or the like.

(Conventional structure and its problems) Conventionally, when inspecting the groove or turn shape of a semiconductor device, it has mostly relied on visual inspection, which requires considerable skill and often requires long inspection times. Automatic inspection equipment has been in demand since it causes considerable eye fatigue.

An example of such an automatic inspection device is one having the configuration shown in FIG. This automatic inspection device will be explained below. The shape to be measured 1 is converted into a spot number by the ITV camera 2, and then binarized by the binarization circuit 3. Further, the reference shape 4 of the shape to be measured is converted into a stain signal by the ITV camera 5 and binarized by the binarization circuit 6, and these binarized signals are input to the mixing circuit 7. In the mixing circuit 7, as shown in FIG. 2, the shape to be measured 10 and the reference shape 11 are overlapped to obtain a hatched portion 12. This shaded portion 12 indicates a positional deviation from the reference shape 11.

Next, the signal output from the mixing circuit 7 enters a pass/fail judgment circuit 8. At this time, the TV monitor 9 displays FIG. 2 on the screen. The quality determination circuit 8 determines quality based on the size of the positional deviation 12. As a method of obtaining the size, as shown in FIG. 4. As shown in Figure 4, a mask 18 having a size within the permissible positional deviation range in the horizontal and vertical directions is made, and the entire TV screen is scanned to ensure that the mask 18 has a positional deviation of 1.
One possible method is to judge whether or not there is a part that fits completely into 2.

However, in the method shown in FIG.
Even if the difference between 15 and 14 exceeds the permissible range, the difference between the vertical positional deviations 15 and 16 may be within the permissible range. In this case, it is not a defect, and on the contrary, the vertical positional deviation is There are cases where the horizontal positional deviation is small even if it is larger than the allowable range, so it is necessary to simultaneously study the horizontal and vertical positional deviations, and the circuit is ?123K.
Becomes I. In addition, in the method shown in FIG. 4, a mask 18 in the horizontal and vertical directions with a positional deviation of 8' is created, and since all both sides are scanned, it is equivalent to making four measurements in the horizontal and vertical directions at the same time. 18, it is necessary to simultaneously observe as many TV scanning lines as the permissible vertical positional deviation range, and a device with a larger permissible range requires a larger circuit configuration and is difficult to manufacture.

(Object of the Invention) The present invention solves these problems and provides a shape inspection device that can easily determine the acceptability of a pattern shape of a semiconductor device or the like with a simple circuit configuration.

(Structure of the Invention) In order to achieve the above object, the shape inspection device of the present invention separately converts the shape to be measured into an electrical signal and the reference signal including the permissible positional deviation range of the shape to be measured. A level setting section that sets the level to a constant ratio, a mixing circuit section that combines these to obtain a composite signal, a level difference detection section that detects the level difference from the composite signal, and a level difference detection section that sets the level so that the level difference is constant. It is characterized by comprising a pass/fail determination circuit section that determines pass/fail by observing an increase or decrease in order.

With this configuration, by superimposing the permissible positional deviation range of the shape to be measured on the signal of the shape to be measured as a signal level difference, the circuit processing for pass/fail judgment only requires horizontal and vertical positional deviation judgments in the horizontal direction.

(Explanation of Examples) Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 5 shows a block diagram of a shape inspection device according to the present invention. In the figure, 19 is a shape to be measured, and 21 is a reference shape. In the present invention, first, the shape to be measured 19 is converted into an electrical signal by an ITV camera 20, and the reference shape 21 is
The V camera 22 converts the signals into electrical signals, and the level setting circuits 23 and 24 set the levels of these signals. At this time, the reference shape 2] is the shape 3 of the allowable H range m1 when it is larger than the measured shape No1 (the quasi-shape 29) as shown in FIG.
As shown in FIG. 7, the shape 31 of the tolerance range in the case of 0 and small is expressed by the difference in the electrical signal level. FIG. 7 shows the signal level at part 32 in FIG. 6. A low signal level 33 in FIG. 7 indicates a shape 30 with a large tolerance for the reference shape 29;
shows a shape 31 when the tolerance range of the reference shape 29 is small. If the difference between signal levels 33 and 34 is "1", then the difference between signal levels 35 and 33 is "3" and "6", which is three times the difference.

When converting the measured shape 19 into an electrical signal and mixing it with the reference shape 21 in the mixing circuit 25, the signal level is determined by the level setting circuits 23 and 24 according to the level difference between 33 and 34 as shown in FIG. , 36 and 34 are set to twice the level difference. These are added to the mixing circuit 25 and synthesized. As shown in Figure 9, the composite signal is created by adding the reference signal in Figure 7 and the electrical signal of the measured shape in Figure 8.The level difference is 38 and 37 if 37 and 34 are 2", 39 and 38 become "°3", and the level difference is 1x and 2x.

It increases by 3 times and decreases by 3 times, 2 times, and 1 times.

Here, when the shape to be measured is larger than the tolerance range of the reference shape as shown in Figure 10, 40 is the shape to be measured, 30 is the reference shape when the tolerance is large, 31 is the reference shape when the tolerance is small, and 41 is the part. The signal level is as shown in FIG.

In other words, the level difference is "2", "l" 11
3 I+, 2x, 1x.

It increases by 3 times and decreases by 3 times, 1 time, and 2 times. In addition, when the shape to be measured is smaller than the allowable range of the reference shape as shown in FIG.
As shown in FIG. 13, the signal level at part 3 is the level difference ``i,= ,3''.

It becomes "2" and increases 1x, 3x, 2x, and 2x.

It decreases by 3 times and 1 times. If it is large, the 2x level difference will appear before the 1x or 3x level difference. Also, if it is small, 1
It will come after twice or three times.

As a result, the quality of the measured shape can be judged by observing that the level difference increases sequentially by 1, 2, and 3 times, and decreases by 111 times, 3 times, 2 times, and 1 times. I can do it.

The level difference detection circuit 26 extracts the υ level difference from the composite signal of the signal under test and the reference signal synthesized by the mixing circuit, and the pass/fail judgment circuit 27 determines the order in which the level differences occur. It is detected and a pass/fail judgment is made. 28 is TV
A monitor displays the composite signal on the screen.

Even if the shape to be measured becomes larger in the vertical direction of the screen, as shown in 44 in Figure 14, the level of part 45 becomes 2" as shown in Figure 15, and it is possible to judge pass/fail by not starting from 1x. .Furthermore, when there is a measured shape 44 between the reference shape 30 with a large tolerance range and the reference shape 31 with a small tolerance range, as in the part 46 in FIG. 14, the level difference is as shown in FIG. 16.
1”.

"2" increases by 1 and 2 times, decreases by 2 and 1 times, increases sequentially, and decreases sequentially, so it can be determined that it is within the permissible range.

(Effects of the Invention) As is clear from the description of the above-mentioned actual sister example, the shape inspection device of the present invention has the following advantages.

(1) Combine the signal of the i1+11 fixed shape with different signal levels depending on whether the positional deviation tolerance of the measured shape is large or small, such as ↓a, and make a pass/fail judgment by focusing only on the change in the level of the synthesized signal. Therefore, one measurement of the positional deviation between the signal of the shape to be measured and the signal of the reference shape is not counted as the number of cores.

(2) Regarding the vertical shape determination of the TV screen, it is possible to determine whether the screen is good or bad by simply determining the level change in the horizontal direction.

(3) Since the composite signal includes the allowable range information of the reference signal of the shape to be measured, the circuit configuration for pass/fail determination becomes simple.

[Brief explanation of drawings]

Fig. 1 is a block configuration diagram of a conventional example, Figs. 2, 3, and 4 are composite diagrams of a reference shape and a measured shape to explain the conventional example, and Fig. 5 is an example of the present invention. &r IT, +l j
==-J-,,,lI-A4mel+IP White r C
1iJ71 a 1 n l191 Composite diagram of the quasi-shape and the measured shape, FIGS. 7 and 8. 9, 11, 13, 15, and 16 show the signal levels of the reference shape and the measured shape in the same embodiment, or the base f (the level of the composite signal of the shape and the measured shape). 20.22...ITV camera, 29...Basic [phase] shape, 30...Reference shape when the tolerance range of the measured shape is large, 31...Reference when it is small. showing shape, 34
...Signal level O of the part without the measured shape and reference shape Fig. 1 Fig. 2 Fig. 0 Fig. 3 Fig. 4 Fig. 5 Fig. m-” Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 Figure 12 Figure 13 Figure 14/15 16th. 4mu

Claims (2)

[Claims] (1) A means for converting a shape to be measured into an electrical signal, a means for generating a reference electric signal having a different signal level depending on whether the allowable range of positional deviation of the shape to be measured from a reference position is large or small; means for adjusting and mixing the signal level of the electrical signal of the measurement shape between different signal levels of the reference electrical signal to obtain a composite signal, and a change in the signal level of the composite signal increasing or decreasing at a constant rate; 1. A shape inspection device comprising: a pass/fail determining means for determining pass/fail by determining whether or not the object is present. (2) In the above means for generating a reference electrical signal and the above means for obtaining a composite signal by mixing the electrical signal of the shape to be measured and the reference electrical signal, the different signal levels of the reference electrical signals are set at a ratio of 1:3. The shape inspection device according to item (1), wherein the electric signal level of the shape to be measured is set to twice the smaller of the different signal levels and mixed to obtain a composite signal.